Classifiers cyclone

Mular, A.L. and W. R. Bull, W.R. (Editors), Mineral Processes Their Analysis, Optimization and Control, Queens University, Ontario (1969) Mular, A. L. and N. A. lull, N.A., The Selection of Cyclone Classifiers, Pu ps and Pump Boxes for Grinding Circuits, Mineral Processing Plant Design , AIME, New York (1978)... 

Air classification is perhaps the simplest fly ash processing option and is normally employed to improve the fineness of the ash (i.e., remove coarse particles). A typical cyclone classifier uses centrifugal force to separate fine particles from an air stream. The particles enter tangentially into a cylindrical chamber dispersed in an air stream and centrifugal force forces the coarser particles to the wall of the cylinder while the air stream and finer particles spiral to an inner vortex. The air exits from the inner core via an outlet port while the particles slide down the chamber walls and exit the bottom. 

Hya Irocyclone The wet cyclone classifier has rapidly achieved prominence since the 1950s and continues to gain popularity throughout chemical and ore-dressing industries. Standout virtues are its low capital cost and ability to make extremely fine separations by proper adjustment of design/operating condition. See Fig. 19-23. 

In 1898, George Barton patented a new process where molten lead was rapidly stirred and atomised into small droplets, which were then carried away and oxidised by a humidified air stream drawn through die pot. The resulting oxide was passed through a series of cyclone classifiers where the larger particles were separated and returned back to the reaction pot for further processing, while the fine powder was collected in silos (drums or hoppers). 

At Rum Jungle, the feed to this type of process is provided by passing the normal acid leach pulp through a cyclone classifier system. The sands are easily removed and washed at a fraction of the cost of a filtration or decantation system. The residual pulp contains about 20 per cent solids, of particle size mostly between 200 and 300 mesh, and these are difficult to remove before a normal static column ion-exchange process. 

Cyclone Classifier. A dust-laden gas enters a cylindrical or conical chamber tangentially and leaves through a central opening. The dust particles, moving in a helical path, experience a force towards the centre of Mv/r, where M is the particle mass, v the particle velocity and r the radius of the chamber. Thus particles are separated according to size, by a force which can be 5 to 2500 times that due to gravity in a settling tank. The... 

K. H. Schwambom and H. J. Smiderrsky, Improved Dedusting of Powders in Cyclone Collectors and Cyclone Classifiers, Powder Handling Processing, 3/96 pp.257-258... 

An alternative drying technique which neatly avoids the problems of forming hollow particles is that of fluidised bed spray granulation In this process a "seed" powder is used which is passed through a fluidised bed and coated with a fresh l iyer of slip on each pass. Using cyclone classifiers, the size and size distribution of the particles can be controlled. To date, this process has not found widespread usage, primarily because of the high capital cost of the equipment. 

Sodium sihcate (41°Bh, 1 3.22 ratio Na20 Si02) is added in the milling operation to disperse the slime, mosdy kaolin. Dispersion also aids the grinding process. The rod mill serves to grind the ore to 0.833 mm (—20 mesh) or to the point where mica, quart2, feldspar, and iron minerals are Hberated. Cyclones, or rake, hydrauhc, or other types of classifiers, are used after grinding to produce coarse and fine mica fractions that are treated separately. 

The hydrocyclone, commonly referred to simply as cyclone, is a nonmechanical sedimentation-type classifier (2,6,10,27) (Fig. 7). It has no moving parts or power attachments directly connected to it. The hydrocyclone has become the workhorse of most mineral processing operations because of its simplicity, short residence time, compactness, and low cost of operation. It is, however, characterized by lack of sharpness of separation. Equipment... 

Although performance curves are valuable in assessing classifier performance, frequently the cyclone overflow size analysis is used more than the d Q of the cyclone. In practice, clusters of cyclones (in parallel) are used to handle large capacities. Cyclones are manufactured in sizes ranging from 0.01 to 1.2 m in cyclone diameter, ie, the cylindrical section at the top (2,10). Capacities mn from 75 to 23,000 L/min. Materials of constmction vary widely. Rubber-lined or aH-polyurethane cyclones are used when abrasion is a problem. 

Cla.ssifica.tion. Slurry leaving precipitation is classified into a coarse and one or more fine fractions, usually by elutriation in hydroclassifiers. Cyclones and combinations of hydroclassifiers and cyclones are gaining popularity. In smelting grade alurnina plants, the coarse fraction, called primary product, is sent to calcination the fine fractions, called secondary and tertiary seed, are recycled to be grown to product size. 

For acid mists, the Brink impactor is often used (Fig. 10) (17). The mist is first drawn through a cyclone to remove particles larger than 3 fim. A five-stage impactor is used to classify mist particles of diameter 0.3—3.0 fim. 

For vibrating screens, the suitable parameter A is the screen deck area multiphed by the length in m. Cost includes dtive- and feed-boxes, and excludes motor, starter, and screen cloth. For spinal classifiers, the suitable parameter A for costing is the spinal diameter, in cm. Cost includes the motor. For hydtocyclones, the suitable parameter A for costing is the cyclone diameter, in cm. Cost includes fittings and combination urethane-ceramic liners. The appropriate values of X and the coefficients ate given in Table 4. 

Etibank is the sole producer of boron minerals and derivatives in Turkey, which is second in production only to the United States. The open-pit Kirka mine in the Eskisehir Province is the only source of Turkish sodium borate ore. A tincal concentrate is produced from ore that has been blasted and carried in tmcks to the concentration plant. The ore is screened and cmshed to reduce it to —100 mm and then hammer milled to —25 mm. The stockpiled material is further milled and screened to 6 mm. A fraction of +1 mm (+18 mesh, U.S. Standard) is washed and classified to remove fine clay. Clay is removed from the —1 mm faction bypassing it through cyclones and then through a classifier. This material is centrifuged and combined with the washed + 1 mm faction to produce a final product which is a —6 mm concentrate having 6—8 wt % moisture and 32% 2 3 1987 production was... 

The product from each stage of grinding is classified by size, and the oversize material is recycled to be ground further. Wet cyclones are the most common type of classifier. 

Ball mills or tube mills can be operated in closed circuit with external air classifiers with or without air sweeping being employed. If air sweeping is employed, a cyclone separator may Be placed between mill and classifier. (The principles of size reduction combined with size classification are discussea under Characteristics of Size Classifiers. ) Likewise other types of grinding mill can be operated in closed circmt with external size classifiers (Fig. 20-12), as will be described at appropriate places on succeeding pages. However, many types of grinders are air-swept and are so closely coupled with their classifiers mat the latter are termed internal classifiers. 

An improved version of the Raymond classifier sends all the air to the prodiict-collector cyclone, returning only sohds. This improves... 

Figures 20-43 to 20-44 illustrate single-stage and two-stage closed-circuit wet-grinding systems. The circuits or Fig. 20-59 may also be used as a closed-circuit wet-grinding system incorporating a hquid-solid cyclone as the classifier.

Sizing crushing, screening, classifying Particulates (dust) Local exhaust system and cyclones... 

The termination of the cone section is the apex orifice. The critical dimension is the inside diameter at the discharge point. The size of this orifice is determined by the application involved and must be large enough to permit the solids that have been classified to underflow to exit the cyclone without plugging. The normal minimum orifice size would be 10% of the cyclone diameter and can be as large as 35%. Below the apex is normally a splash skirt to help contain the underflow slurry in the case of a hydroclone. 

A) crossflow classifier (B) hydraulic classifier (C) hydrocyclone (D) cyclone. 

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